docs: def format_field(self, field):
          """ Format a single Dynamo value """
          if field is None:
              return "NULL"
          elif isinstance(field, TypeError):
              return "TypeError"
          elif isinstance(field, Decimal):
              if field % 1 == 0:
                  return str(int(field))
              return str(float(field))
          elif isinstance(field, set):
              return "(" + ", ".join([self.format_field(v) for v in field]) + ")"
          elif isinstance(field, datetime):
              return field.isoformat()
          elif isinstance(field, timedelta):
              rd = relativedelta(
                  seconds=int(field.total_seconds()), microseconds=field.microseconds
              )
              return delta_to_str(rd)
          elif isinstance(field, Binary):
              return "<Binary %d>" % len(field.value)
          pretty = repr(field)
          if pretty.startswith("u'"):
              return pretty[1:]
          return pretty